load_file.rs

pub struct LoadFile<'a> {
    path: Option<&'a str>,
    data: Mutex<Option<mq::fs::Response>>,
}

impl LoadFile {
    pub fn new(path: &str) -> LoadFile {
        LoadFile {
            path: Some(path),
            data: Mutex::new(None),
        }
    }
}

impl Future for LoadFile {
    fn poll(self: Pin<&mut Self>, ctx: &mut task::Context) -> Poll<Self::Output> {
        if let Some(path) = path.take() {
            let waker = ctx.waker().clone();
            mq::fs::load_file(path, move |response| {
                *self.data.lock() = Some(response);
                waker.wake();
            });

            match self.data.lock() {
                None => Poll::Pending,
                Some(response) => Poll::Ready(response),
            }
        }
    }
}